Cements, mortars, and cementitious compositions are well known and widely available. Their make-up and properties vary widely enabling many and varied end-use applications. For example, many cements, mortars and cementitious compositions are employed in structural applications for buildings, roadways, bridges, wall construction, boat hulls, walkways, and the like. Additionally, they have many applications in non-structural applications, some of which are functional, for example, floor coatings, roofing tiles, furniture, urns, ornaments, and the like, and others non-functional, such as stucco, skim-coat, and other wall coatings, the latter being mostly decorative in nature.
Cements, mortars and cementitious compositions have and continue to evolve as the applications and demands of those applications expand. Oftentimes the evolution takes the form of a variation in the formulation, i.e., using the same constituents in different amounts. Other times the evolution takes the form of new formulations altogether, especially those employing newly identified ingredients that provide new and/or enhanced properties not otherwise attainable. Perhaps one of the most significant advancements in cements and mortars has been the addition of curable/polymerizable organic materials, especially urethane-based and/or epoxy-based materials to the traditionally inorganic mix of the cement, mortar or cementitious composition. Such compositions are described in, for example, Shearing et. al.—U.S. Pat. No. 3,763,070 and U.S. Pat. No. 4,211,680 and Alexander et. al.—U.S. Pat. No. 4,127,548, and provide fast setting, highly durable surfaces, especially for floorings.
Despite the strength and durability of these materials, a number of environmental factors greatly affect their longevity. For example, for those end-use applications exposed to the outdoors environment, acid rain and deicing salts and like compositions degrade and breakdown the hardened cements, mortars and cementitious compositions. However, perhaps the most insidious bad actor on hardened cements, mortars and cementitious compositions are microbes, namely bacteria, molds, mildew, algae and the like. These microbes, particularly certain bacteria, readily degrade the hardened cements, mortars and cementitious compositions. Others, especially, the molds, mildew and algae, render them unsightly and may introduce health concerns as well.
An area of particular concern is in cement, mortar and cementitious flooring systems. Such flooring systems find wide use in food and food processing facilities, pharmaceutical and biopharmaceutical facilities, and research, especially biotechnology, facilities due to their high durability. This is because such flooring must be washed repeatedly with highly caustic solutions to ensure the removal of all bacteria and the like to avoid contamination of food stocks and pharmaceuticals and related processing equipment and the like as well as to maintain containment of micro-organisms employed in bio-pharmaceutical and biotechnology applications.
Over the years, many different attempts have been made to provide antimicrobial performance and characteristics to cements, mortars and cementitious compositions. Maeda et. al.—JP 04-149053 and Hori et. al. JP 11-079920 describe the addition of difficult to dissolve metals and metallic oxides and water soluble metal compounds, respectively, into concretes, mortars and the like used in sewer systems to attack sulfur oxidative bacteria. Atsumi et. al., JP 04-154651 describe the addition of silver, copper or zinc containing calcium phosphate-based compounds, especially tricalcium phosphate and hydroxyapatite, to traditional mortars for producing mildew-proofing joint filling materials. Similarly, Yamazaki et. al.—JP 11-171629 describes the addition of an antimicrobial metal containing hydroxyapatite to mortar and concrete slurries for instilling antimicrobial properties to the hardened materials. Haraguchi—JP 11-157907 describes a mortar composition containing, among the traditional components, an aqueous resin emulsion and an antimicrobial agent. Morioka—JP 09-002849 describes forming calcium aluminate-based glass powders containing antimicrobial metal salts as antimicrobial/antimildew additives for hydraulic cements. Shigeru et. al.—JP 06-256052 and JP 06-247820 describe various cements and gypsum having incorporated therein cuprous oxide alone or in combination with a silver-containing powder for alga-proofing, antifungal and antimicrobial effects. Ong et. al.—US 2005/0106336 A1 describe cementitious slab products formed from a composite material of a natural aggregate, a cementitious matrix and an antimicrobial agent. Haraguchi JP 11-029375 describes a surface finishing material for mortars and cements comprising an antimicrobial agent compounded into a cement mortar. Additionally, Ramirez Tobias et. al. describe concrete-based floor and wall coverings having an organic antimicrobial agent incorporated therein.
While such efforts have helped control bacterial, mildew and algal growth, the use of such antimicrobial additives is at a cost, not just financially, but also with respect to the properties of the cement, mortar and cementitious materials themselves. In order to achieve reasonable, commercial performance, considerably high loadings of the antimicrobial additives is necessary. This adds significant costs to an otherwise low cost product. Additionally, as one adds more and more antimicrobial agents to enhance their intended performance, there is an effect on the properties of the modified materials, especially on their color and appearance. Thus, there is still a need for an antimicrobial additive and antimicrobial cements, mortars and cementitious compositions that have high antimicrobial performance relative to their level of incorporation. Additionally, there is a need for such compositions that have enhanced antimicrobial performance with the same or less antimicrobial additive than found with the mere addition of such additives as described in the art.